Ungelatinized starch products of improved properties and method of making the same



UNGELATINIZED STARCH PRODUCTS OF 11"- PROVED PROPERTIES AND METHOD OF MAK- INC THE SAME Carlyle G. Caldwell, North Plainfield, N. J., assignor to National Starch Products Inc., New York, N. Y., a corporation of Delaware No Drawing. Application May 19, 1954 Serial No. 430,983

20 Claims. (Cl. 260-2333) This invention is a continuation-in-part of my co-pending U. S. application Serial No. 756,106, filed June 20, 1947.

My invention relates to the production of starch products of improved properties. More specifically, it relates to the treatment of starches whereby they attain greater stability and clarity of the cooked pastes, greater resistance to gelling of the pastes upon cooling, and lowered gelatinization point, as compared to the corresponding untreated starch material.

The improved properties set forth above are of particular importance in the manufacture of adhesives, the use of starch as a thickening agent in foods and the sizing and fabrication of certain types of textiles and papers. Qf particular significance from the standpoint of industrial utilization is the fact that such starches, when cooked in the presence of acids or salts, show less loss of their viscosity and clarity than do the corresponding untreated starches.

It is the prime object of the present invention to produce starch derivatives having the above properties and to devise a method for the ready production of said products. Other objects will become apparent from the ensuing specification.

In this specification the term starch includes starch from any source, such as corn, wheat, potato, tapioca, waxy maize, sago, sweet potato and the like, and also starches which have been converted, either by acid hydrolysis, oxidation or other means.

I have discovered that starch derivatives of these and other improved properties of commercial importance may be formed by the production of starch derivatives containing sulfonic acid groups. This production can be eflected either by reacting raw starch with suitable reagents or by reacting certain unsaturated, ungelatinized starch derivatives with a chemical containing the sulfonic acid group, such as a bisulfite. In either event, the improved starch derivative of the present invention is characterized by containing a sulfonic acid group.

When unsaturated starch derivatives are employed, it is desirable that the starch unsaturation be caused by an ethylenic double bond as shown-diagrammatically by the following formula:

(CaH Os):-CeH904R(i'=C-B:

wherein R may be and wherein, if both R, and R are hydrogen, R must be a member of the first group consisting of formyl, cyano, carboxy, carbalkoxy and carbalkyl radicals, and if either R or R or both are members of the second group consisting of the first group and alkyl, aryl and substituted alkyl and aryl radicals, R need not be a member of the first group. An example of the first type of derivative in which both R and R are hydrogen is United States, a e

s 2,825,727 Ice Patented Mar. 4, 1958 the tapioca starch ester of itaconic acid (see Example VII). An example of the type of derivative in which both R and R are not hydrogen is the potato starch ester'of citraconic acid (see Example III). Examples of the type of derivative in which only one of the radicals R and R are not hydrogen are the corn starch ester of maleic acid in which either R or R is a carboxy radical (see Example I) and the tapioca starch ester of crotonic acid in which either R or R is an alkyl radical (see Example II). In all of these examples, in which either R or R or both are not hydrogen, R is hydro gen, but this is not essential to the carrying out of my invention. To put the matter in another way, if R is not one of the radicals of the first group, but instead may be hydrogen, then either R or R or both must be a member of the second group.

It will be noted that I have excluded that type of unsaturated derivative in which R ond R are hydrogen and R is not a radical chosen from the first group. I have then found that the use of this latter type of unsaturated derivative produces a completely difierent type of product from that of my present invention, this product being described in U. S. Patent No. 2,668,156.

Various derivatives of starch may be reacted with bisulfite for the purposes of this invention. Among the suitable starch derivatives into which sulfonic acid groups may be introduced are, for example, certain of the starch esters prepared according to the method described in U. S. Patent No. 2,461,139. In accordance with that method, certain starch esters are made by treating starch in aqueous suspension with alkali and with anhydrides of organic acids containing double bonds, such as the anhydrides of maleic, citraconic, itaconic and crotonic acids. It is to be understood, however, that the practice of my invention is not limited to starch derivatives made by any particular method, the only limiting factor being that the starch derivatives treated must contain unsaturated radicals of the type described, the unsaturation being due to the presence of an ethylenic double bond.

The treatment of unsaturated starch derivatives with bisulfite, according to my invention, can be carried out in aqueous suspension, at temperatures below the gelatinization temperature of the starch or starch derivative. This makes it possible to filter and wash the resultant starch producta fact of considerable importance in the industrial application of this process.

Although in dealing with complex reactions of the type under discussion, analysis of the molecular changes involved cannot be carried out with absolute precision, it is believed that the action of the bisuliite such as sodium bisulfite on the unsaturated starch derivative causes a saturation of the derivative by the attachment of the bisulfite group to one of the unsaturated carbon atoms on the chain. Thus, if the corn starch ester of maleic acid, which has the general form starch-O-C- l =C-COOH is appropriately reacted with sodium bisulfite, the resultant starch derivative will, it is believed, exhibit the molecular structure While the sulfonic acid group is here illustrated as being attached to the alpha carbon of the free carboxyl group, it might instead be attached to the beta carbon of the free carboxyl group. It is the starch derivative having the probable molecular form shown which exhibits the desired characteristics.

' it-should be-no'ted that the various unsaturated starch derivatives which Iemploy'as, for example, those made by the process of the above-listed Patent No. 2,461,139 have been so trcatedthat the g anulestructureot the starch has not been destroyed, and the substitution of the hydroxyl groupshas probably-taken place on thesurface cine granule; According to theiprocess of'my present invention, the unbroken granule'of thestarch is 'retained;'

in-other words, the addition of the sulfonic 'acid groups probably takes place with unsaturated groups on' the stirface ofthe granule, and again, there is, therefore, :a relatively low degree of substitution. s V Although; as stated above, the bisulfite addition can take place inaqueous suspension, it has been found that theadditionoffthe sulfonic acid group to the unsaturated radical also takes: place readily if the unsaturated starch ungelat'inize'd starch granule containing sulfonic acid groups, which granule corresponds to the molecular'structu're previously set forth, by utilizing' 'ra'w starch (that is; starch which doesinot contain the unsaturated .radica1s).. This ungelatinized raw starch is treated with" alkali and witha compound which contains both a sulfonic acid group andagroupcapable of reacting with the hydroxyl groups'in thestarch toproduce starch ether-s er esters. Thus, there results an ether or ester derivative of starch which contains sulfonic acid groups. In order to 'cause, substantial reaction of these acids with starch, it

salt thereof, such as sulfobenzoic anhydride and sulfo- 'phthalic 'anhyd'ride. p

i It will be seen that I have indicated here the production of two types of starch derivatives containing sulfonic acid groups, i. e., starch esters and starch ethers. As compared to the starch esters, starch ethers and raw starch from which they are produced, the products of my in? vention are altered in the following-respects:

(l) The cooked suspensions, or pastes, areclear'er and more translucent. I r (2) The cooked suspensions, orpas'tes, exhibit a legsened tendency "to set 'to a gel upon cqolin'gl l property, in-a starch,,of resistance to gelling of its cooked suspensions is known as stability..- Q

(3) The gelatininatio'nitemperature is lower.

(4) The clarity and viscosityot1the ;:cooked starch pastes are less sensitive to the presence of acids and salts;

that is, they do not losefclarity and thin out in the presence of acids and saltsto the eXtcnt'that starch-'deriva 'tives containing only 'carboxyl groups. would do.

(5) In many cases theyhave increased water absqrp 7 tion. That is, they may be cooked with a larger qu'a'ln tity of water than the r'aw starch 'or the untreated starch has been found that ratherhigh concentrations of alkali are ordinarily advisable,v and as will be seen from the examples hereinafter given, we use as much as 4.5% alkali based on the starch, although it is understood that the amount of alkali must be limited to that which will permit the said mentioned reaction with the hydroxyl groups in the starch. It has already been explained that 7 gelatinization of the starch is to be avoided, and since this ;high alkali content would ordinarily cause gelatinization' of thestarch granules, it is advisable to suspend thestarch in .a concentrated sodium sulfate solution before addition ofthe. alkali and the subsequent addition of the :ether'or ester-forming derivative. The .sodium sulfate prevents gelatinization of the starch in thepresence of the high alkali concentrations needed for this reaction. This anti-gelatinization eiiect is apparent even at temperatures up to 100 C. Of course, it ispossibleto use lower quantities of alkali so as to avoid gelatinization, making unnecessary the useof-sodium sulfate, but a considerably lower degree of substitution results. Examples of reagents of this type which combine the functions f ether-formation and .sulfonic acid addition are starch etherifying reagents having a sulfonic acid group ora salt thereof and also having either a halogen, epoxy or ethylenic group, such aschloromethylo-isethionic acid (CICH CHOHCH SO H) berizyl chloride para sulfonic acid (clam-4031!) a,b:unsaturated olefinic sulfonic acids such as vinyl sul fomc acid (CH CHSOJ'I), 2,3-epoxy ,1 propane sulfonic'acid 7 ononcn son! 3 chloro 2 hydroxy 1' propane sulfonic acid and salts of said acids; suitable esterification reagents includeorganic acid anhydrldes containing a sulfonic ac d gr p 9 3 ester or ether to produce a paste of a given viscosity. a

Products may also be preparedwhose viscosity is unchanged, or even thinner, depending upon the desired ultimate application. y

When I refer to treatment with bisulfite, it isunderstood that I mean sodium, Potassium or ammonium bi sjulfite or any other acid salt of sulfurous acid. p The degree of improvement brought about by the process of my invention depends upon the following variables:

(1) The-proportion of unsaturated radicals in the starch to be treated with bisulfite. The greater the Ip'r'oportion of unsaturated radicals present in the starchjthe greater theam'ount of sulfonic acid groups whi'chin'ay thus be introduced into the starch. Excellent results have been obtained using starches containing from lfunsaturated radical per '140'anhydroglucose units up to 1 unsat- 7 urated radical per 15-anhydroglucose units. [In those.

cases where one reacts raw starch with a compound contaming both a sulfonic acid group and agroup capable of reacting with the hydroxyl 'groupsin the starch,'roughly "the same range applies namely, the introduction of 7 from 1 sulfonic group per 140 anhydroglucose units inthe starchto l sulfonic group per 15 anhydroglucose units;

( 2) The proportion of bisulfite'use'd, based on the unsaturated radicals in the starch. 'At room temperature, with about. a 'four hour period of treatment, I prefer to use an amount of bisulfite equal to seven-fold the stoichi'o metrical amount calculated upon the weight of the 1111-. saturated radical.

C., an equivalent result is obtained by using only about four times the stoichiometri'cal amount required by the weight of the unsaturated radical in the starch. On the other hand, far-lower amounts of bisulfite can be used but with proportionatelylesser degree of substitution.

(3) The period of treatment. A'longer period of treatment permits decreased temper ture and/or decreased amount of bisulfitei (4) Temperature. The temperature of the reaction aifects the other variables; At higher temperatures, the

inver'sely'proportional to the temperature and amount of: reagent. Referring to increased temperatures, it should be remembered that at temperatures above 50 C. there be the problem, in aqueous media, of gelatiniz'ation of he sta h; h s, owe r. can be o r m by caus ing out the reaction ina saturated sodium sulfate solution, as previously described. V I

At higher temperatures, say at 505 xample I This example illustrates .e treatment of a corn starch ester of maleic acid with sodium bisulfite.

100 parts of corn starch ester of maleic acid (starch-OC-CH=GHCOOH) containing approximately 1 maleic acid ester radical per 28 anhydroglucose units is suspended in 200 parts of water in which is dissolved 15 parts of sodium bisuliite. The mixture is stirred for 4 hours at room temperature. The starch product is then filtered and washed. The resultant product has the improved properties previously described, namely, increased water absorption, greater clarity, lessened tendency of the cooked paste to gel upon cooling, lowered gelatinization temperature, and less sensitivity to acids and saltsall as compared to the starch ester prior to introduction of the sulfonic acid groups.

Example II This example illustrates the treatment of a tapioca starch ester of crotonic acid with potassium bisulfite.

100 parts of tapioca starch ester of crotonic acid containing 1 crotonic ester radical per 26 anhydroglucose units is suspended in 260 parts of water in which is dissolved 8 parts of potassium bisulfite. The suspension of starch is stirred for three hours, maintaining the temperature at 50 C. The starch is then filtered and washed. The resultant product exhibits the improved properties described in Example 1.

Example 111 This example illustrates the treatment of potato starch ester of citraconic acid with ammonium bisulfite.

100 parts of potato starch ester of citraconic acid containing 1 citraconic acid ester radical per 19 anhydroglucose units is suspended in 260 parts of Water in which is dissolved 25 parts of ammonium bisulfite. After stirring the suspension for 6 hours at room temperature, the starch is filtered and washed. The improved properties described in Example I are also noted in this product.

Example IV This example illustrates the treatment of an unmodified starch wherein the unmodified starch is reacted with a compound which contains the sulfonic group.

100 parts of unmodified corn starch is suspended in 200 parts of Water in which has been dissolved 3.5 parts of caustic soda and 75 parts of sodium sulfate. There is then added 5.6 parts of sodium benzyl chloride para sulfonate. The mixture is stirred and heated at 60 C. for 4 /2 hours. The alkali is then neutralized with acid and the starch is filtered and washed, resulting in the improved product previously described.

Example V This example, like the previous one, illustrates the treatment of an unmodified starch.

100 parts of unmodified corn starch is suspended in 200 parts of Water in which has been dissolved 4.5 parts of sodium hydroxide and 75 parts of sodium sulfate. There is then added parts of sodium chloromethylo isethionate (ClCH CHOHCH SO Na). The mixture is stirred at room temperature for 17 hours. The alkali is then neutralized with acid and the starch filtered and 6 washed. This product also exhibits the improved properties previously noted.

Example VI This example illustrates the treatment of a corn starch ester of maleic acid with sodium bisulfite. It differs from Example I in that a starch derivative is used which contains a greater proportion of maleic acid ester radicals and uses a larger proportion of bisulfite.

160 parts of corn starch ester of maleic acid containing 1 maleic acid ester radical per 15 anhydroglucose units is suspended in 209 parts of water in which is dissolved 25 parts of sodium bisulfite and 75 parts of sodium sulfate. The mixture is stirred for 4 hours, maintaining the tem perature at 75 C. The starch is then filtered and Washed. T he sodium sulfate is used in this example because the elevated temperature would otherwise cause gelatinization of the starch.

Example VII This example illustrates the treatment of a starch derivative with bisulfite-alcohol suspension rather than in an aqueous medium. 100 parts of tapioca starch ester of itaconic acid containing 1 itaconic ester radical per 26 anhydroglucose units is suspended in 300 parts of ethyl alcohol, containing dispersed therein 5 parts of sodium bisulfite. The mixture is refluxed for 4 hours. The starch product is then filtered and washed in the usual manner, exhibiting the improved properties previously described.

Example VIII This example illustrates the etherification of starch with sodium-3-ch1oro-2-hydroxy-l-propanesulfonate.

parts of anhydrous sodium sulfate and 8 partsof sodium hydroxide are dissolved in 250 parts of water.

200 parts of corn starch are then suspended in this solu-' tion, with agitation, followed by the addition of 8 parts of sodium 3-chloro-2-hydroxy-l-propanesulfonate.

as compared to the corresponding untreated starch.

Example IX This example illustrates the esterification of starch with sulfobenzoic anhydride.

parts of corn starch are suspended in parts of water. The pH is adjusted to 9 with a 3% aqueous solu-' tion of sodium hydroxide;

There are then slowly added 5 parts of sulfobenzoic anhydride dissolved in 60 parts of acetone, maintaining the pH between 8.5 and 10.0 by additions of a 3% aqueous sodium hydroxide solution. After all of the sulfobenzoic anhydride has been added, the pH is neutralized to 6 and the starch is filtered, washed and dried. The

resulting product, when cooked in Water, is heavier and clearer than a sol made with the corresponding untreated starch, and after cooling it is more stable.

Example X Mr part portions of sulfophthalic anhydride, maintaining Y -17 the pHgEctween 7 and 10':by the addition ofaqneous 3% sodium hydroxide solution. After 1 0 :parts 'of sulfophthalic anhydride have been added, agitation is c0n-.-

tinued for one hour, with thepH at approximately 8. The material is then neutralized to pH 6, and the starch is'filter'ei washed'and dried. The resulting product gelatinizes in water much more readily than untreated corn starch, giving a product which is heavier when hot, and

considerably more stable upon cooling.

Referring again to U. S. Patent 'No.'2,46l ,l39, methods are there described whereby ung'elatinized starches are treated in watersuspen'sion with alkali'and certain organic acid anhydrid'e's at'a pH within the range 7. to ll.- The improved properties of 'the starch so treated, as compared to the raw, untreated/starch, are similar, although to a ,less'erdegree, to the improved qualities obtained in my present process. In otherwords, the starch esters produced by the organic acid anhydride treatment of the above mentioned patent exhibit the properties of increased .water absorption, greater clarity, and stability, as compared to the untreated starclr The starch products now produced by the presentmethod of introducing sulfonic groups into the starch molecule exhibit a further improvement in these same qualities of clarity, stability, and frequently water absorption, as previously described.

In the above-mentioned patent, the efiect of the organic acid anhydrides upon the starch properties was attributed with the hydroxyl groups in the amylose, or linear frac' tion of the starch, could be considered as taking the form of side groups or branches, thus preventing the linear amylosemolecules. from becoming oriented in a closely parallel fashion with each other and with the linear portions of the amylopectin or branched molecule frac tion of the starch, and'thereby resulting in the prevention of association of the starch molecules, through hydrogen bonding between the hydroxyl groups." In this manner the retrogradation or setting of the starch to .a

gel is prevented.

With reference to my present invention wherein sulfonic acid groups are introduced into the starch molecule, it is believedthat the further improved properties are due to the fact that sulfonic acid groups are, in general,

more acidic (that is, more highly dissociated) thancarboxylic acid groups and,.in consequence, have even greater :affinity for water than do the carboxyl groups. i

V The characteristics of' controlled Water absorption,

greater clarity and greater resistance to gelling as well as lowered gelatinization temperature point to obvious commercial and industrial uses for the product of my invention, It is of value in adhesives and also as a thickenin'g agent in foods and other manufactures. Also of particular; significance isthe resistance of the product of my invention to break down upon cooking in the presence of acidsor salts, The manufacture of food preparations such, as salad dressings, pie fillings and the like frequently involves'cooking, of starch or starch derivatives in the presence of acids and/or salts and, as stated, the starch of my invention shows substantially less tendency to loss of viscosity and clarity under such conditions, as compared to the corresponding untreated starches. It is, of course, understoodthat before using any particular starch derivative info'eds, its non-toxicity must first be investigated and fullyzcstablislied; a I V I These. same. improved qualities give the products of m invention great value in textile and paper sizing and fabri cation. It "is adaptable-tome manufacture er-paper beiajier sizes because of the increased retention of the starchgin the paper fibers. The characteristic of lowered gelatinization temperatures is of particulariin'terest in the preparation ofstarc'hes requiring lower temperatures for cookingand shorter cooking times. i i i I claim: 7

1. An ungelatinized starch. derivative selected from the class consisting of: (a) the reaction product of raw starch with starch etherifying reagents having a sulfonic acid group and salts thereof and also having a g'roup from the class'consisting of halogen, epoxy and ethylenicfgroups under reaction conditions such that gelatinization willflnot take place and under such limited alkalinity conditions that the etherifying agent reacts with 'hydroxylfgroupfiiqf the starch, said reaction product. containing from one sulfonic group 'per anhydroglucose units inith'e starchj tb one sulfonic group per 15 'anhydroglucose units; (1;) the reaction product of raw starch with starch 'esteriifying re:- agents comprising organic acid 'anhydride's containing} sulfonic acid group and salts thereof, under reaction con ditions such that gelatinization Will not take place, and

(c) the reaction product of a member selected. from the class consisting of sulfurous acid and the acid salfsfof sulfurous acid with an unsaturated starch derivatiiie having anethylenic double bond of the type (cannot)...armor-3 0 042;

1 l ll}: which R is a member selected from the class consisting o n in whi it h R2 n R3 f r peasant as be 'a 'member selected'from the first class consisting of,

formyl, cyano, carboxy, carbalkoxy and carbalkyl radicals and in which, ifeither R or R or both are members of the second class consisting of formyl, cyano, carboir'y, alkyl, aryl and substituted alkyl and aryl radicals, then R must be a member selectedrfrom the'class consisting of hydrogen and the radicals of the second class, the said ungelatinized starch derivative being characterized by re taining the unbroken granular structure of the raw starch.

2. A starch derivative comprising the reaction product of a member selected from the class consisting o f sul furous acid and the acid salts of sulfurous acid with fan unsaturated starch ester having an ethylenic double bond a member selected'from' the first class consisting of @formyl, cyano, carbox'y, carbalkoxy and carbalkyl radicals, and in which, if either R or R or both are members a selected from the second class consisting of formyl,cyano, 'carboxy, alkyl, aryl and substituted alkyl and aryl radical's, then R must be a member selected from theclass consisting of hydrogen. and the radicals of 'jthe second class. a i

3. A starch derivative comprising the reaction'product of a member selected from the class consisting of sulfurous acid and the acid salts of sulfurous acid with-an unsaturated starch ester having an ethylenic double bond of the type (CaHroOs);.CoHuO;-R 53-11:

R1 Rt 7 in which R is and in which, if both R and R are hydrogen, R must be a member selected from the first class consisting of formyl, cyano, carboxy, carbnlkoxy and carbalkyl radicals, and in which, if either R or R or both are members selected from the second class consisting of formyl, cyano, carboxy, alkyl, aryl and substituted alkyl and aryl radicals, then R; must be a member selected from the class consisting of hydrogen and the radicals of the second class.

4. An ungelatinized starch derivative comprising the reaction product of raw starch with an etherifying agent comprising sodium chloromethylo-isethionate under reaction conditions such that gelatinization will not take place and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

5. An ungelatinized starch derivative comprising the reaction product of raw starch with an etherifying agent comprising sodium-3-chloro-2-hydroxy-1 propanesulfate under reaction conditions such that gelatinization will not take place, and under such limited alkalinity conditions that the ethen'fying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

6. An ungelatinized starch derivative comprising the reaction product of raw starch with an etherifying agent comprising vinyl sulfonic acid, under reaction conditions such that gelatinization will not take place, and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

7. An ungelatinized starch derivative comprising the reaction product or" a member of the class consisting of sulfurous acid and the acid salts of a sulfurous acid with a starch ester of maleic acid under reaction conditions preventing gelatinization from taking place, the said ungelatinized starch derivative being characterized by retaining the unbroken granular structure of raw starch.

8. An ungelatinized starch derivative comprising the reaction product of a member of the class consisting of sulfurous acid and the acid salts of a sulfurous acid with a starch ester of crotonic acid under reaction conditions such that gelatinization will not take place.

9. A method of lowering the gelatinization point and improving the stability of an ungelatinized, unsaturated starch derivative having an ethylenic double bond of the form in which R is a member selected from the class consisting of and in which, if both R and R are hydrogen, R must be a member selected from the first class consisting of formyl, cyano, carboxy, carbalkoxy and carbalkyl radicals and in which, if either R or R or both are members selected from the second class consisting of formyl, cyano, carboxy, alkyl, aryl and substituted alkyl and aryl radicals, then R must be a member selected from the class consisting of hydrogen and the radicals of the second class, which comprises reacting such an ungelatinized starch derivative with a member of the class consisting of sulfurous acid and the acid salts thereof.

10. The method of claim 9, in which the ungelatinized starch derivative is reacted with sodium bisulfite.

11. The method of claim 9, in which the ungelatinized starch derivative is reacted with potassium bisulfite.

12. The method of claim 9, in which the ungelatinized starch derivative is reacted with ammonium bisulfite.

13. The method of claim 9, in which the ungelatinized starch derivative is held in aqueous suspension.

14. The method of claim 9, in which the ungelatinized starch derivative is held in non-aqueous suspension.

15. The method of claim 9, in which the ungelatinized starch derivative is reacted in a medium of ethyl alcohol.

16. A method of lowering the gelatinization point and imp-roving the stability of an ungelatinized, unsaturated starch derivative which comprises reacting raw starch with a member of the class consisting of (a) starch etherifying reagents having a sulfonic acid group and salts thereof and also having a group from the class consisting of halogen, epoxy and ethylenic groups, the reaction be ing under conditions such that gelatinization will not take place and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units, and (12) organic acid anhydrides containing a sulfonic acid group and salts thereof as starch esterifying reagents, in the presence of alkali under reaction conditions such that gelatinization will not take place.

17. A method of lowering the gelatinization point and improving the stability of an ungelatinized, unsaturated starch derivative which comprises reacting raw starch with an etherifying agent comprising sodium chloromethylo-isethionate in the presence of alkali under reaction conditions such that gelatinization will not take place, the reaction being under conditions such that gelatinization Will not take place and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

18. A method of lowering the gelatinization point and improving the stability of an ungelatinized, unsaturated starch derivative which comprises reacting raw starch with an etherifying agent comprising sodium 3-chloro-2 hydroXy-l-propanesulfate in the presence of alkali under reaction conditions such that gelatinization will not take place, the reaction being under conditions such that gelatinization will not take place and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

19. A method of lowering the gelatinization point and improving the stability of an ungelatinized, unsaturated starch derivative which comprises reacting raw starch with an etherifying agent comprising vinyl sulfonic acid in the presence of alkali under reaction conditions such that gelatinization will not take place, the reaction being under conditions such that gelatinization will not take place and under such limited alkalinity conditions that the etherifying agent reacts with hydroxyl groups of the starch, said reaction product containing from one sulfonic group per 140 anhydroglucose units in the starch to one sulfonic group per 15 anhydroglucose units.

20. A method of lowering the gelatinization point and improving the stability of an ungelatinized, unsaturated starch derivative which comprises suspending raw starch in a concentrated sodium sulfate solution, adding alkali and then adding a starch etherifying reagent having a sulfonic acid group and salts thereof and also having a group from the class consisting of halogen, epoxy and ethylenic groups under reaction conditions such that gelatinization will not take place, and under such limited alkalinity conditions that the etherifying agent reacts UNITED STATES PATENT OFFICE 3 Certificate of Correction W Patent No. 2,825,727 March 4. 1958 Carlyle G. Caldwell It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 18, for 0nd read and; column 3, line 68, for

(CH CHSO H) read (CH =CHSO H);

column 9, line 21, and column 10, line 45, for propanesulfate, each occurrence, read propanesulfonate.

Signed and sealed this 23rd day of September 1958.

Attest KARL H. AXLINE, ROBERT C. WATSCN, Attestz'ng Oyfioer. Commissioner of Patents. 

1. AN UNGELATINIZED STARCH DERIVATIVE SELECTED FROM THE CLASS CONSISTING OF: (A) THE REACTION PRODUCT OF RAW STARCH WITH STARCH ETHERIFYING REAGENTS HAVING A SULFONIC ACID GROUP AND SALTS THEREOF AND ALSO HAVING A GROUP FROM THE CLASS CONSISTING OF HALOGEN, EPOXY AND ETHYLENIC GROUPS UNDER REACTION CONDITIONS SUCH THAT GELATINIZATION WILL NOT TAKE PLACE AND UNDER SICH LIMITED ALKALINITY CONDITIONS THAT THE ETHERIFYING AGENT REACTS WITH HYDROXYL GROUPS OF THE STARCH, SAID REACTION PRODUCT CONTAINING FROM ONE SULFONIC GROUP PER 140 ANHYDROGLUCOSE UNITS IN THE STARCH TO ONE SULFONIC GROUP PER 15 ANHYDROGLUCOSE UNITS; (B) THE REACTION PRODUCT OF RAW STARCH WITH STARCH ESTERIFYING REAGENTS COMPRISING ORGANIC ACID ANHYDRIDES CONTAINING A SULFONIC ACID GROUP AND SALTS THEREOF, UNDER REACTION CONDITIONS SUCH THAT GELATINIZATION WILL NOT TAKE PLACE, AND (C) THE REACTION PRODUCT OF A MEMBER SELECTED FROM THE CLASS CONSISTING OF SULFUROUS ACID AND THE ACID SALTS OF SULFUROUS ACID WITH AN UNSATURATED STARCH DERIVATIVE HAVING AN ETHYLENIC DOUBLE BOND OF THE TYPE 